In a large bowl, stir together flour, baking powder, salt, soda, and sugar until thoroughly blended.
Cut butter into chunks, add to bowl, and rub mixture together with your fingers until the largest pieces are no more than about 1/4 inch in diameter.
Pour in buttermilk and stir with a fork until dough sticks together and clings to the fork in a large lump.
Turn dough onto a flour-dusted board, turning gently to coat all surfaces lightly with flour.
Then knead, making about 10 turns.
Place dough in a lightly greased 9 or 10-inch round or square pan (a cake pan or frying pan that can go into the oven).
Pat dough out evenly to fill pan.
With a flour-dusted 2 to 3-inch round cutter, cut straight down through dough, then lift cutter straight up to make each biscuit; cut close together to make as many as possible.
Leave scraps in place.
Bake in 400° oven for 15 to 20 minutes or until golden brown on top.